In a known robot system in the related art, a transport device transports a workpiece from one place to another, and robots perform operations on the workpiece at their positions. The workpiece needs to be fixed so as not to move during transportation by the transport device or during the operations performed by the robots. Typically, a chuck-type tool, which can open and close, and an electric cylinder or an air cylinder, which drives the tool open and closed, are used to fix the workpiece.
Meanwhile, a chuck-type robot hand that grips and releases a workpiece not by using a driving device such as a cylinder but by using urging forces of springs is known (for example, see Japanese Unexamined Patent Application Publication No. 2016-196071, and Japanese Unexamined Patent Application Publication No. Hei 08-197474).